As the number of carbon atoms in a chain increases the boiling point of alkanes

Options

A. Increases
B. Decreases
C. Remains same
D. May increase or decrease

Explanation

**Step-by-Step Solution:**

1. **Understanding Alkanes**: Alkanes are hydrocarbons with the general formula CnH2n+2, where 'n' is the number of carbon atoms. They are saturated compounds, meaning they contain only single bonds between carbon atoms.

2. **Boiling Point Trends**: As the number of carbon atoms (n) in an alkane increases, the boiling point of the alkane tends to increase. This trend can be attributed to the increase in molecular size and mass.

3. **London Dispersion Forces**: The boiling point of alkanes is influenced by intermolecular forces. As the number of carbon atoms increases, the surface area of the molecule also increases, leading to stronger London dispersion forces (a type of van der Waals force). These forces arise due to temporary dipoles that occur when electron clouds around atoms fluctuate.

4. **Direct Proportionality**: The boiling point of alkanes is directly proportional to:
- The number of carbon atoms in the chain: More carbon atoms lead to higher molecular weight and stronger London forces.
- The molecular mass of the alkane: Higher molecular mass generally correlates with higher boiling points due to increased London forces.
- The degree of branching: More branching in the carbon chain tends to lower the boiling point because branched alkanes have a more compact structure, reducing surface area and thus the strength of London forces.

5. **Conclusion**: Therefore, it can be concluded that as the number of carbon atoms in an alkane chain increases, the boiling point of the alkane increases due to the increase in molecular mass and the strength of intermolecular forces.

---